Marceli Wein

Interactive skeleton techniques for enhancing motion dynamics in key frame animation

A significant increase in the capability for controlling motion dynamics in key frame animation is achieved through skeleton control. This technique allows an animator to develop a complex motion sequence by animating a stick figure representation of an image. This control sequence is then used to drive an image sequence through the same movement. The simplicity of the stick figure image encourages a high level of interaction during the design stage. Its compatibility with the basic key frame animation technique permits skeleton control to be applied selectively to only those components of a composite image sequence that require enhancement.

Tablet-based valuators that provide one, two, or three degrees of freedom

The ability of the user of a graphics system to interactively control the motions of 3-D objects enhances his or her spatial perception and comprehension of those objects. This paper describes several logical devices based on the tablet, each particularly suited to control some type of interactive manipulation of 2-D and 3-D objects in real time. The “turntable” and the “stirrer” convert rotary motion of the tablet pen or puck into values for one-axis rotational control; the “rack”, a two-axis device, is used for scaling control; for three-axis rotational control, the tablet-based three-axis trackball is particularly suited.

A multitasking switchboard approach to user interface management

A Switchboard model of user input management is presented which takes advantage of opportunities afforded by a multitasking multiprocessor programming environment. This model further separates application programming from the programming of the interaction dialogues as compared with conventional user interface management systems. It also provides powerful tools for implementing parallel forms of input, is suitable for managing interaction in window-based systems, and is very flexible.The paper describes this Switchboard model and its implementation on top of the Harmony operating system, as well as discussing some of the graphics support needed for the model.

Evolution is essential for software tool development

We examine the problems encountered in evolving software development tools, in particular, configuration management tools, drawing on our experience in producing the DaSC configuration management toolset. Building good software development tools is a time-consuming, iterative process where the tool designers must take into account the evolving nature of the software development process embodied in the tools, the evolving nature of the environment in which the tools exist, and the evolving understanding that the tool designers have of the users of the tools. We believe that our experience with the tools that we have developed is applicable to other kinds of tools used in industrial settings.

Hidden line removal for vector graphics

A system for removing hidden edges in line displays of three dimensional scenes is described. The hardware system is relatively low cost, and operates on several hundred vectors in real-time. The system consists of a graphics peripheral connected to a PDP 11/55 computer and a software package to drive the peripheral. As each convex object is displayed, the occlusion hardware extracts the silhouette and retains it in a one-plane “matte memory”. As subsequent objects, taken from a priority ordered list, are displayed, the vector generator tests the contents of the frame buffer at the coordinates along the vector. The contents of the matte memory determine which portions of the vector should be intensified. To produce the priority ordered list of objects, the software algorithm uses three ordering techniques applied selectively to different potions of the scene. One technique, used for ordering unconstrained pairs of objects is described in detail.

Mass market computers for software development

W. Morven Gentleman and Mardi Wein Software Engineering Laboratory, Institute for Information Technology National Research Council of Canada Ottawa Ontario Canada KIA OR6 <surname> @iit. nrc. ca The mass market or applitmce computer lends itself well to being used for software development and leads to a different style of development. By being truly personal, it provides a focus for all professional activities of a developer. The primary form of software used on such computers is shrink wrapped software, which has profound implications how the software is used and causes the make-or-buy trade-off to take on an entirely new meaning. This environment, consisting of a network of mass market computers, has infhsenced the development of a novel source management scheme, a summary of which is given here.

Dynamic illustrative graphics for simulations

Abstract In any graphics application, the environment created by the system designer is of utmost importance. A variety of good input devices, effective real time displays, ease of interaction with graphical elements and with system instructions can all contribute to a friendly environment. A graphics system designed for simulations with a facility for adding both abstract dynamic graphics and user control is enhanced by the addition of features uncommon to other graphics systems. These features, and their values and the ways in which they contrast with more traditional graphics systems, will be described.